<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        function Person(name,age){
            this.name = name
            this.age = age
        } 
        Person .prototype.sayHi = function(){
            console.log('hellow'+'=====>'+this.name);
            
        }
        function Student(name){
            this.name = name 
        }
        var per = new Person('feng',9)
        var stu = new Student('wnag')
        per.sayHi.apply(stu)
        // per.apply()
    </script>
</body>
</html>